The aim of the study was to develop a family conflict scale for family caregivers of persons with dementia in long-term care facilities and to explore the relationship between family conflicts and family support.

The scale was developed through forward- and back-translations, interviews with 12 staff members in long-term care facilities, and cognitive interviews with 12 family caregivers who met operational definitions in this study. The test was conducted with 334 family caregivers and a retest was conducted with 318 family caregivers who had indicated willingness to participate further.

The internal consistency was relatively high for all subscales (Cronbach's α >0.87); sufficient retest reliability was demonstrated for all subscales (intraclass correlation coefficient >0.69). Confirmatory factor analysis supported a three-factor model. Convergent and discriminant validity for each of the family conflict scale subscales, family APGAR, and the Symptom Check List–90 Items–Revised were acceptable. Family caregivers who received no family assistance for caregiving perceived more conflict in their family than those receiving family assistance.

The Japanese version of the family conflict scale for family caregivers of persons with dementia in long-term care facilities was developed. The reliability and validity of the scale were verified. When providing support to family caregivers in long-term care facilities, it is necessary to consider the family from multiple viewpoints, including family conflicts and support conditions from other family members.